Colloidal molybdenum complexes and their preparation



United States Patent i 3,223,625 COLLOIDAL MOLYBDENUM COMPLEXES ANDTHEIR PREPARATION Elmer B. Cypher-s, Cranford, Richard F. Neblett,Plainfieid, and Charles S. Lynch, Lebanon, N.;!., assignors to EssaResearch and Engineering Company, a corporation of Delaware No Drawing.Filed Nov. 12, 1963, Ser. No. 323,151 The portion of the term of thepatent subsequent to July 14, 1%1, has been disclairned 14 Claims. (Cl.252-18) This invention concerns colloidal molybdenum complexes, theirpreparation, and improved lubricating oil compositions containingmolybdenum complexes. The invention is particularly directed to thepreparation of molybdenum complexes for use as antiwear additives forlubricating oils by a novel process that involves dispersion of an etherextract of a molybdenum compound in a dispersant material. Thisapplication is a continuationin-part of application Serial No. 131,723,filed August 16, 1961, and abandoned after the filing of the presentapplication.

It has been known for some time that molybdenum sulfide is a desirableadditive for lubricating oils because of its ability to reduce frictionand hence to minimize wear of the parts being lubricated. Although it ispossible to prepare lubricating oil compositions containing molybdenumsulfide by grinding the material to exceedingly fine particle size andthen dispersing it in lubricating oil, the dispersion is not completelystable and the particles of molybdenum sulfide tend to settle out. Thissettling may result because of an improperly formed colloid or it may becaused by changes occuring in the oil on standing or in use. There hasbeen a need for more stable dispersions of molybdenum sulfide or,alternatively, a need for compositions exhibiting the wear-reducingproperties of molybdenum sulfide but being free of the unstable natureof molybdenum sulfide dispersions.

While it has recently been found that colloidal dispersions ofmolybdenum sulfide can be prepared in situ in lubricating oils byreacting an aqueous solution of the molybdate with hydrogen sulfide in alubricating oil medium containing a dispersant material and subsequentlyremoving water, that process carried with it the limitation that inorder to operate at high molybdenum levels more dispersant wasnecessary.

It has now been found that colloidal complexes having increasedconcentrations of molybdenum in proportion to the dispersant can beprepared in the following manner: an aqueous solution of a molybdenumcompound as, for example, ammonium molybdate or molybdic acid in amineral acid as, for example, 6 N aqueous HCl is prepared. This solutionis then extracted with an ether, for example, ethyl ether, and then theether solution is dispersed in an oil-soluble dispersant and the etheris subsequently removed. If the stripping gas used for removing theether contains hydrogen sulfide, at least some molybdenum sulfide isformed in the product.

Not only does the process of this invention lead to higher molybdenumconcentration levels, but it also enables wider versatility in theselection of dispersants that may be used; e.g., calcium compounds wherebarium compounds are objectionable; sulfonate detergents (nonlabilesulfur) or sulfur-free dispersants where active sulfur compounds (e.g.phosphosulfurized compounds) are objectionable. Alternatively, a highmolybdenum concentration obtained in accordance with the presentinvention, even if the dispersant had certain drawbacks, would require arelatively small amount of the latter and would permit the concurrentuse, in the finished lubricant, of a second, more desirable dispersantfrom the standpoint of Patented Dec. 14, 1965 "ice deleterious efiectsin use, even though the second dispersant might be less satisfactory forpreparing the colloidal dispersion of molybdenum compounds in accordancewith this invention, thus giving a highly satisfactory composition fromevery standpoint.

Any water-soluble compound of molybdenum wherein the molybdenum ispresent in the hexavalent state may be employed as the molybdenum sourcein the practice of this invention. Such compounds include molybdic acid,ammonium molybdate, sodium molybdate, potassium rnolybdate, other alkalimetal molybdates, and other molybdenum salts such as M0001 MoO Br Mo OCl and MoOF Molybdenum trioxide may be employed by dissolving it inaqueous ammonia followed by treatment with hydrochloric acid which inessence, converts the oxide to molybdic acid or ammonium molybdate.

The general procedure followed in practicing the invention is asfollows. It is usually desirable to dissolve the molybdenum compound inthe minimum amount of water necessary for complete solution, althoughthe amount of water may range from 4 to 10 parts by weight per part ofmolybdenum com-pound. Then sufiicient mineral acid, preferably aqueousHCl, is added to furnish a solution having a normality in the range of 4to 8, preferably 5 to 7. If the acidity is greater than 7 N, there maybe deleterious effects. For example, there is a tendency for excesschlorine to appear in the product if I-ICl has been used. If the acidityis below 5 N, the molybdenum utilization, i.e., the proportion ofmolybdenum in the product to the molybdenum used in the process, tendsto be poor.

Preferably, the acidified solution is cooled to below 50 C. before theether extraction to minimize evaporation losses. The required coolingwould not be as great in a closed system. After a period of agitationfor proper contact with the ether and then a period of settling forseparation, the ether extract layer is added to a suitable dispersant.Contacting temperatures and mixing rates are controlled so as to preventfoaming problems. The ether is then removed by either (1) heat andvacuum, (2) heat and inert gas blowing, or (3) heat and H 8 blowinguntil a temperature of about 200 F. is reached followed by vacuum orinert gas blowing to remove excess H 5. Nitrogen is a suitable inert gasand is relatively less expensive than other inert gases, e.g. helium.The procedure involving H S treating is preferred since this converts atleast a portion of the product to colloidal molybdenum sulfide andensures good antiwear properties. Extraction of the acidic solution ofthe molybdate is preferably conducted with ethyl ether. Other ethers maybe used also. For example, tetrahydrofuran can also be employed when itis mixed with hexane to decrease its water solubility. Other etherswhich are at least partially insoluble in water or which can beextracted from water, are also useful. Preferably, the ethers are thoseranging from 3 to 8 total carbon atoms; more preferably, those having 4to 6 total carbon atoms. Ethers having more than 8 total carbon atomsare not excluded.

It is possible to employ extraction ratios as low as one part of etherper part by weight of molybdate or equivalent molybdenum compound. Ingeneral, however, the ether extraction step will involve the use of fromabout 10 to parts of ether per part of molybdate or equivalent. Theratio of dispersant to molybdenum will depend largely on the basicity ofthe dispersant, because the latter should be sufficiently basic andshould be used in sulficient quantity to neutralize the free acid in theether extract. Also, the dispersant should be oil-soluble. Suitabledispersants include metal hydrocarbon sulfonates, metal carbonate sols,metal alkyl phenates, metal alkyl phenol sulfides, reaction products ofmetal oxides and/ or metal hydroxides with phosphosulfurizedhydrocarbons, and certain nonmetallic dispersants as describedhereinafter. The preparation of the complex of the invention may be madein the presence of the dispersant per se but it is usually moreconvenient to conduct the preparation in an oil concentrate of thedetergent or dispersant. Such concentrates usually contain from about 10to about 80 wt. percent, preferably 20-60 Wt. percent, of the dispersantin a lubricating oil. The lubricating oil may be either a mineral oil ora synthetic oil, the latter including diesters, complex esters,'polysilicones, polyglycols and the like.

The sulfonates used as dispersants in practicing this invention are theoil-soluble alkaline earth metal salts of high molecular weight sulfonicacids obtained by the sulfonation of either natural or synthetichydrocarbons. Sulfonic acids can be prepared by treating lubricatingbase stocks with concentrated or fuming sulfuric acid in a conventionalmanner to produce oil-soluble mahogany acids. These sulfonic acidsgenerally have molecular weights in the range of about 300 to 700.Petroleum sulfonates are well known in the art. Suitable sulfonic acidscan also be produced by sulfonating alkylated aromatic hydrocarbons suchas benzene, toluene, and xylene alkylated with olefins or olefinpolymers. For example, sulfonated didodecyl benzene may be used.

Specific examples of sulfonates suitable for practicing this inventioninclude calcium petroleum sulfonates, barium petroleum sulfonates,calcium di-C alkyl benzene sulfonate, barium di-C alkyl benzenesulfonate and calcium C alkyl benzene sulfonate. The C alkyl groups canbe derived from dissobutylene, the C alkyl groups can be obtained fromtripropylene and the C alkyl group can be obtained fromtetraisobutylene. It is preferred to use the so-called high alkalinitytype of sulfonate, which is prepared by reacting metal base in excess ofthat required for simple neutralization of the sulfonic acid to form analkaline product which can then be treated with carbon dioxide to reduceits free alkalinity and form a substantially neutral final product. Itis believed that the high alkalinity sulfonates are primarilydispersions of metal carbonates in the neutral sulfonates.

Metal salts of alkyl phenols and of alkyl phenol sulfides are also wellknown in the art. Metal salts of alkyl phenols having straight-chain orbranch-chain alkyl groups of from to 20 carbon atoms are usuallypreferred, and the metal used to form the phenate is preferably analkaline earth metal, e.g., calcium, barium, strontium, or magnesium,although other salts such as those of aluminum, sodium, cobalt, lead,chromium, or tin are sometimes used. A specific example is the bariumsalt of the alkylation product of phenol with tripropylene. Metal saltsof the corresponding alkyl phenol sulfides may also be used. The latterare the thioethers and polysulfides of alkyl phenols, i.e., compounds inwhich the alkyl groups are joined by one or more divalent sulfur atoms.The alkyl phenols can be converted to phenol sulfides by reaction withsulfur dichloride. If sulfur monochloride is used, the resultingproducts are primarily alkyl phenol disulfides. Specific examples of thephenate sulfides include barium tertiary octyl phenol sulfide, calciumtertiary octyl phenol sulfide, barium-calcium nonyl phenol sulfide,barium tertiary amyl phenol sulfide, calcium dodecyl phenol sulfide, andbarium nonyl phenol sulfide. Preferably, the metal phenols and metalphenol sulfides are of the high alkalinity type (i.e. of high metalcontent) prepared by reacting the metal salts with excess metal base.

The reaction products of phosphosulfurized hydrocarbons with alkalineearth metal oxides or hydroxides can be prepared by first treating ahydrocarbon with the phosphorus sulfide and then reacting the productwith an alkaline earth hydroxide or oxide, for example, bariumhydroxide, preferably in the presence of an alkyl phenol or an alkylphenol sulfide and also preferably in the presence of carbon dioxide.

The phosphosulfurized hydrocarbons may be prepared by a reaction of asulfide of phosphorus such as B 3 with a suitable hydrocarbon materialsuch as a terpene, a heavy petroleum fraction or a polyolefin. Theolefin polymers that are employed have Staudinger molecular weights inthe range of 500 to about 200,000 and contain from 2 to 6 carbon atomsper olefin monomer. Particularly preferred are the polybutenes havingStaudinger molecular weights in the range of about 500 to about 200,000.Polymers of ethylene, propylene, butylene or isobutylene may be used,for example. The phosphosulfurized hydrocarbon can be prepared byreacting the hydrocarbon base stock with from 5 to 30 weight percent ofa sulfide of phosphorus, and preferably with from 10 to 20 weightpercent of phosphorus pentasulfide. The reaction is conducted underanhydrous conditions at temperatures from about to about 600 F. for fromabout V2 to 15 hours. The preparation of phosphosulfurized hydrocarbonsis more fully described in U.S. Patent 2,875,188.

Nonmetallic dispersants that may be employed in the present inventioninclude the condensation products of alkenylsuccinic anhydrides andpolyamines and the condensation products of alkenylsuccinic anhydrides,polyamines and carboxylic acids, said products having residual aminogroups to impart basicity.

The preparation of reaction products of high molecular weightalkenylsuccinic anhydrides with various polyamine compounds is taught inU.S. Patents 3,024,195 and 3,024,237 and also in British Patent 922,831.The teaching in the U.S. patents referred to is that alkenylsuccinicanhydrides having alkenyl radicals derived from hydrocarbons of 400 to3000 molecular weight can be reacted with amine derivatives ofpiperazine. The British patent referred to teaches that alkenylsuccinicanhydrides, as, for example, a polyisobutenylsuccinic anhydride, can bereacted with polyamines such as tetraethylene pentamine, diethylenetriamine, triethylene tetramine, and the like.

The preparation of reaction products of alkenylsuccinic anhydrides withcarboxylic acids and alkylene polyamines is disclosed and claimed incopending application Ser. No. 241,174 of Norman Tunkel et al., filedNovember 30, 1962. Brieflly, those reaction products are prepared by thesimultaneous reaction of about 0.5 to 1.5 mole proportions of a C to Ccarboxylic acid, about 1 molar proportion of an alkylene polyamine, andabout 1.0 to 1.5 molar proportions of an alkenylsuccinic anhydridewherein the alkenyl group contains in the range of from about 40 toabout 250 carbon atoms, the reaction being effected by heating thereactants together until an oil-soluble product is obtained.

While the reactants, i.e. the alkenylsuccinic anhydride and thepolyamino compound (and, when used, the carboxylic acid), upon simplemixing will interact to some extent, the products will generally beoil-insoluble. However, upon heating (e.g. to about 200-250" F.) thereaction mixture will become mineral-oil-soluble, and upon continuedheating condensation reactions will begin to take place with theevolution of Water. The evolved Water can be readily removed by blowingnitrogen or other inert gas through the reaction mixture during thecourse of the reaction. The reaction may be carried out by heating thereactants for about 1 to 30 hours at 250 to 350 F. Preferred reactionconditions include heating for 6 to 20 hours at 275 to 300 F.

The preparation of an alkenylsuccinic anhydride is Well known in the artand simply involves reacting maleic anhydride with an organic compoundhaving an olefinic linkage. Generally, about equal molar proportions ofmaleic anhydride and the olefinic material are merely heated together.

The hydrocarbon radicals may be either straight-chain or branched chainand they may be either substituted, as for example, chlorinated orsulfurized, or they may be unsubstituted, and they will includealiphatic, acyclic and aromatic radicals. Preferably, the total numberof carbon atoms in the hydrocarbon groups is within the range of fromabout 40 to 250, more preferably within the range of from about 50 toabout 120. Particularly desirable for use, because of low cost and readyavailability, are alkenyl groups obtained by reacting maleic anhydridewith a polymer of a C to C monoolefin wherein the polymer has amolecular weight within the range of from about 300 to about 3000 ormore. Especially useful products are obtained when the molecular weightrange is from about 500 to about 1500. As specific examples, the alkenylgroup may be derived from polypropylene or polyisobutylene, e.g.,polyisobutylene of 780 molecular weight or of 1200 molecular weight.

The aliphatic polyamine that is employed in preparing the reactionproducts of the present invention may be an alkylene polyamine fittingthe following general formula:

where n is 2 to 3 and m is a number from to 10. Specific compoundscoming within the formula include diethylene triamine, tetraethylenepentamine, dipropylene triamine, octaethylene nonamine, andtetrapropylene pentamine. N,N-di-(2-aminoethyl) ethylene diamine mayalso be used. Other aliphatic polyamino compounds that may be used arethe N-aminoalkyl piperazines of the formula /N-R ca om wherein n is anumber 1 to 3, and R is an amino-alkyl radical containing 1 to 3 carbonatoms, for example, N,N'-di-(2-aminoethyl) piperazine.

The use of mixtures of alkylene polyamines, mixtures of N-aminoalkylpiperazines, and mixtures of the alkylene polyamines with theN-aminoalkyl piperazines is also contemplated.

When preparing reaction products of the alkenylsuccinic anhydrides withthe alkylene polyamines and/or the N-aminoalkyl piperazines, equimolarproportions of the alkenylsuccinic anhydride and the nitrogen-containingmaterial are usually employed, although in some instances an excess ofthe anhydride or of the nitrogen compound can be used. Similarly, whenpreparing the reaction product of an alkenylsuccinic anhydride, apolyamine and a carboxylic acid, equimolar proportions of the threereactants are ordinarly used. However, variation in these relativeproportions can be made, for example 1.0 to 1.5 moles of the anhydrideand 1.0 to 1.5 moles of the carboxylic acid can be used per mole ofpolyamine.

The carboxylic acid component of the reaction mixture, when such isused, comprises a carboxylic acid of from 1 to 30 carbon atoms in analiphatic hydrocarbon chain, which can be either branched or straightchain and either saturated or unsaturated. Both monocarboxylic acids anddicarboxylic acids are included. Preferably carboxylic acids having from1 to 18 carbon atoms are used, including acetic acid, fumaric acid,adipic acid, lauric acid, oleic acid, linoleic acid and stearic acid.

The following examples serve to illustrate this invention.

EXAMPLE 1 An oil-soluble molybdenum complex can be prepared inaccordance with this invention in the following manner: 1 part by weightof ammonium molybdate is mixed with 5 parts of water and an eqal volumeof 12 normal HCl is added, thus giving a 6 normal solution. Thissolution is cooled to about 50 F. and extracted with 21.5 parts of ethylether. Separation into two layers is permitted and the ether laye risthen removed and stirred into 8 parts by Weight of an oil-solubledisperant. The

dispersion is then heated and stripped with gases to remove ether andwater. Until a temperature of about 200 F. is attained, the strippinggas comprises hydrogen sulfide. Heating is continued until a temperatureof about 350 F. is reached, nitrogen gas being used to strip ether and H5 from the dispersions at temperatures above about 200 F. The product isthen filtered.

While the preparation of the complexes may be done in a batch process, acontinuous process may also be used wherein each of the steps will beconducted in a separate zone. The lower layer obtained during theseparation step following the ether extraction step may be recycled tothe step of mixing ammonium molybdate with water and HCl. Also, theether that is removed during stripping can be scrubbed with NaOH forexample to remove H 5, and then be reused for further extraction.

The range of typical product analyses obtained in a number of runs usinga high alkalinity calcium sulfonate as the dispersant is shown in TableI.

Table I PRODUCT ANALYSIS WHERE DISPERSANT IS HIGH ALKALINITY CALCIUMiSULFONATE Weight percent Mo 5 to 6 S 1.4 to 3.4

CO 7.5 to 8.5

Cl 3.5 to 4.0

EXAMPLE 2 A phosphosulfurized hydrocarbon was prepared by re' actingparts by weight of a polybutene having an average Staudinger molecularweight of about 940 with 15 parts by weight of phosphorus pentasulfidefor about 8 hours at 425450 F., the mixture being stirred and blown withnitrogen during the reaction. The resulting phosphosulfurized polybuteneanalyzed about 3.5 wt. percent phosphorus and about 6.6 wt. percentsulfur. Its viscosity at about 210 F. was about 20,000 SSU.

A solution of parts by weight of the phosphosulfurized polybuteneprepared as above was made in 112 parts by weight of a refined minerallubricating oil having a viscosity of SSU at 100 F. To the mineral oilsolution was added 273 parts by weight of a nonyl phenol having anaverage molecular weight of 248. The nonyl phenol was prepared byalkylation of phenol with tripropylene and comprised about 60-65%monononyl phenol and about 35-40% of dinonyl phenol. The mixture ofalkyl phenol, mineral oil and phosphosulfurized polybutene was treatedwith barium hydroxide pentahydrate and carbon dioxide at a temperatureof about 250260 F. for 6-8 hours. The amounts of barium hydroxide andcarbon dioxide used were selected to furnish a weight ratio of barium tophenolic hydroxyl group of about 12 to 1 and a weight ratio of barium toCO of about 4 to 1. Then 339 parts by weight of the resulting product,101 parts of additional phosphosulfurized polybutene, and 60 parts ofadditional mineral lubricating oil of the same viscosity were reactedfor an additional 2 hours at 300 F. and then stripped with nitrogen toremove residual hydrogen sulfide. The product was then filtered. Thefiltered product, which is hereinafter referred to as dispersant A, hadthe following weight percent composition:

Percent Phosphosulfurized polyisobutene 27.0 Alkyl phenol (248 averagemolecular wt.) 11.7 Barium oxide 10.6 Carbon dioxide M 2.5 Mineral oil48.2

EXAMPLE 3 A dispersant concentrate was prepared in the following manner.A blend of 19.8 parts by weight of the phosphosulfurized polybutene ofExample 2, 6.5 parts by weight of nonyl phenol, 1.6 parts by weight ofammonium sulfonate of about 450 mol. wt. and 41.7 parts by weight of aneutral mineral oil of 150 SSU viscosity at 100 F. was prepared. To thiswas added at a temperature in the range of 100130 F., 4.4 parts byweight of commercial ammonium hydroxide of 29% NH content. Then 1 partby weight of water and 16 parts by weight of calcium hydroxide wereadded at a temperature of 120150 F., followed by 9 parts by weight of COadded over a period of 3-4 hours at a temperature in the range of145-160 F. The mixture was then dehydrated by heating to a finaltemperature of about 370 F. and then filtered. The filtered product,which is hereinafter referred to as dispersant B, had the followingweight percent composition:

CO 12.0 Phosphos-ulfurized hydrocarbon 22.5 Nonyl phenol 7.4 Neutralmineral oil 47.4 Ammonium sulfonate 1.7

EXAMPLE 4 This example shows that a countercurrent ether extractionprocess can be used to obtain more highly concen trated ether solutionsso that still larger concentrations of molybdenum may be introduced intothe given dispersant. The same quantity of ether was used to extractthree successive aqueous solutions. As shown in Table II, the successiveextraction of the aqueous solution resulted in additional recovery ofmolybdenum. The total recovery in three extractions with successiveportions of 250 cc. of ether was 76%. Indications are that acountercurrent extraction process could cut the ether requirement inhalf.

Table II containing 11.4% calcium and 16% carbonate as CO and had atotal base number of 319 (i.e. an alkalinity equivalent to 319 mg. KOH/gram). The high alkalinity barium sulfonate was also a commercialproduct available from Enjay Chemical Company as Paranox 30. It was aconcentrate in mineral oil and analyzed about 14.5% barium and had atotal base number of 59.

Each of the molybdenum complexes obtained was a clear product. Themolybdenum contents of each of the products are given in Table II. Thepresence of molybdenum utilization given in the table was calculated ineach case from the ratio of actual molybdenum found to the total amountof molybdenum that could theoretically be incorporated in each of theproducts.

1, a molybdenum complex was prepared by extracting a solution of 90parts by weight of ammonium molybdate in 900 parts of 6 normal HCl with2700 parts of ethyl ether and then adding the ether extract to 500 partsof the dispersant B of Example 3. The filtered product had a molybdenumcontent of 6.78%.

EXAMPLE 7 To a solution of 5 grams of ammonium molybdate (2.75 grams M0)in 25 milliliters of water, 25 ml. of 12 N hydrochloric acid was added.The resulting clear solu- ETHER EXTRAOTIONEOF MOLYBDIO ACID SOLUTIONEther Extractions '250 cc. each portion.

grm. ammonium molybdate in 500 ml. of 6N H01 (Con- Grams M0 in Ether-Aqueous Solution Ether Used to Percent Extract of Orig.

Before After Enrichment No. 1 Fresh No. 1 Fresh 0.0 10.15 10.15 38 No. 1Used Once No. 2 Fresh 0.0 7.27 7. 27 27 N0. 1 Used Twice.-- No. 3 Fresh0. 0 3. 10 3. 10 11 Total from No. 1 Aqueous Solution..- 0. 0 20. 52 20.52 76 N0. 2 Fresh No. 2 Used Once. 7. 27 13.68 6. 41 24 No. 2 Used OnceNo. 3 Used Once 3.10 10.30 7.20 27 Total from No. 2 Aqueous S0luti0n10.37 23. 98 13. 61 51 No. 3 Fresh No. 3 Used Twice 10.30 15. 53 5. 2320 EXAMPLE 5 Using the general procedure outlined in Example 1,molybdenum complexes were prepared using various dis persantconcentrates, including a high alkalinity calcium sulfonate, a highalkalinity barium sulf-onate, and the dispersant A of Example 2. In eachcase the reactants were employed in the ratio of one part ammoniummolybdate, 10 parts of 6 normal HCl, and 20 parts of dispersantconcentrate, and (in the first two cases) 30 parts of ethyl ether (allparts are by Weight). In the preparation using dispersant A, only 18parts of ether were used, employing three successive extractions of 6parts each. The high alkalinity calcium sulfonate was a commerciallyavailable synthetic sulfonate available from the Bryton Chemical Companyunder the name Bryton C-300. It was a 46% concentrate in mineral oil ofa calcium sulfonate of about 420 molecular weight tion was cooled toabout 10 C., after which 25 ml. of water, 25 ml. of tetrahydrofuran and25 ml. of hexane were added. The mixture was agitated and then allowedto stand, causing the separation of an upper layer consisting largely oftetrahydrofuran and hexane. It was determined that this layer contained0.53 gram of molybdenum.

A second extraction of the aqueous layer with 25 ml. of tetrahydrofuranand 25 ml. of hexane yielded a top solvent layer which was found tocontain 0.04 gram of molybdenum. A third extraction with the samequantities of each solvent as in the second extraction gave threelayers. The top layer weighed 32.3 grams and contained 0.81 gram Mo,while the middle layer weighed 2 grams and contained 0.16 gram ofmolybdenum.

By mixing the four solvent layers thus obtained it was possible to forma homogeneous solution containing 1.38 grams of molybdenum, or 50percent of the molybdenum as in Example 1.

EXAMPLE 8 Employing the general procedure outlined in Example 1,molybdenum complexes were prepared using as the dispersant a concentratecontaining 21 weight percent of a calcium petroleum sulfonate. Theconcentrate had a total base number of 283 and analyzed 11.5 weightpercent calcium and 13.6 weight percent CO It was obtained as acommercial product known as Lubrizol 56. Three preparations were madeusing the proportions of ingredients given in Table IV. The molybdenumcontents of the products and the molybdenum utilization data are alsogiven in Table IV. It is seen that more molybdenum can be incorporatedas the ratio of dispersant to ammonium molybdate is increased.

EXAMPLE 9 Additional preparations were made in the manner of Example 1,i.e., extracting an acidified solution of ammonium molybdate with ether,adding the ether extract to a dispersant and then stripping the etherfrom the mixture with gases. In one of these preparations no H 8 wasused, but nitrogen blowing was continued throughout the strippingoperation. As in Example 8, the dispersant was Lubrizol 56. Theproportions of reactants and of ether used in extraction are given inTable V, along with the molybdenum contents of the filtered products.

Table V Preparation D E F* Reactants, Parts by Weight:

Lubrizol 56 200 200 200 Ammonium Molybdate 25 35 25 6 Normal H01 250 350250 Extraction Ether 750 1, 050 750 Molybdenum Content of Product, Wt.Percent- 6. 1 7. 11 5. 23

Prepared without hydrogen sulfide blowing.

EXAMPLE A mixture of 180 pounds (0.180 pound mole) of polyisobutylene ofabout 800 molecular weight and 22.5 lbs. (0.230 pound mole) of maleicanhydride was heated for 24 hours at 450 F. under a nitrogen blanket toform polyisobutenylsuccinic anhydride. The product was found to have asaponification number of 86.6 mg. KOH/ gm. of reaction mixture. A lightmineral lubricating oil having a viscosity of 150 SUS at 100 F. wasadded as a diluent in sufiicient quantity to result in a solutioncontaining 75 wt. percent of the polyisobutenylsuccinic anhydride. Then30 ppm. of Dow Corning 60,000 cs. polymethyl silicone was added as anantifoamant. Next, 17.22 lbs. (0.091 pound mole) of tetraethylenepentamine and 5.46 lbs. (0.091 pound mole) of acetic acid were added.The reaction mixture was then heated at 300 F. for 10.5 hours whilenitrogen was blown through it un- 10 til no more water came off. Thereaction product concentrate, after filtration, contained 2.22 wt.percent nitrogen based on the total product, i.e. the actual reactionproduct and oil diluent. The concentrate had a base number of about 24.

EXAMPLE 1 1 Using the general procedure of Example 1, a molybdenumcomplex is prepared by extracting a solution of 20 parts of ammoniummolybdate in 200 parts of 6 N hydrochloric acid with 500 parts of ethylether and adding the extract to parts of the dispersant concentrate ofExample 10.

EXAMPLE 12 Compositions were prepared using as the base oil a highviscosity index SAE 10W-30 motor oil, containing a copolymeric typeviscosity index improver and a detergent inhibitor comprising astabilized colloidal barium carbonatephenate complex. One compositioncontained 2 weight percent of the additive D of Example 9, and a secondcomposition contained 0.14 weight percent of additive E of Example 9,giving respective molybdenum contents of 0.12 weight percent and 0.01weight percent in the two compositions. Each of the compositions alsocontained as an antioxidant 0.5 weight percent of a phosphosulfurizedterpene marketed commercially as Santolube 394C. A third compositionconsisted of the base oil plus 0.9 wt. percent of a zinc dialkyldithiophosphate in which the alkyl groups were derived from a mixture of35% butyl and 65% amyl alcohols. Each of these compositions wasseparately tested in the Volkswagen Valve Train Wear Test.

In this test, the Volkswagen engine is lubricated with the oil inquestion and the engine is run for a period of 100 hours using thefollowing electronically controlled operating cycle, which iscontinuously repeated for the duration of the test:

(a) Five minutes at 600:25 r.p.m., no load (b) Ten minutes atl200:r.p.m., no load (0) Shut down for one minute.

The oil temperature during the test is the temperature normally reachedby the oil during engine operation; i.e. no attempt is made to hold theoil temperature at a con trolled level.

The wear on each tappet is measured and the wear for the 8 tappets isaveraged. If more than one run in made with the same oil, the resultsfor all runs are averaged. The oil is considered to have failed the testif Wear exceeds 10 X 10" inch on any tappet.

The results obtained in the tests are given in Table VI. It will be seenthat the wear was at a satisfactory level, in each instance where amolybdenum complex of the invention was used and that in no instance didthe wear on any one tappet exceed the permissible 10X 10 inch.Contrasted with this the well-known antiwear additive, zinc dialkyldithiophosphate gave 4 to 7 times as much wear and that the wear on someof the individual tappets was quite high. A run made on a base oilsimilar to that used in the compositions tested, but differing only inthat it contained a slightly greater concentration of thedetergent-inhibitor gave an average tappet wear of 3.5 10 inch, with arange of 0-22.

1 1 EXAMPLE 13 Using as the base oil a refined mineral lubricating oilof SAE 30 viscosity grade compounded with 3.5 Weight percent ofdispersant A of Example 2 and 0.5 weight percent of thephosphosulfurized terpene antioxidant known as Santolube 394-C, blendswere made with additive E of Example 9 and with the additive of Example6, in each case using suflicient of the additive to furnish 0.025 weightpercent of molybdenum in the composition.

Each of these blends was tested in the Well-known, 4- ball wear testingmachine. The test was conducted as follows. The test lubricant wasplaced in the cup of the machine and heated to 150 C. The test cupcontains 3 steel balls which are fixed in position by a screw cap. Afourth steel ball, held in a chuck, is pressed against the 3 lower ballswith a force of kilograms and is rotated at 1800 r.p.m. for a period of10 minutes. At the end of the test, the amount of wear is determined bymeasuring the diameter of the wear scar on each of the balls andaveraging the results.

The results obtained in the 4-ball wear test with each of the aboveblends, as well as with the base oil, are given in Table VII. It will beseen that there was less wear with either blend than with the base oil.

Table VII Oil blend: 4-ball wear, mm. Base oil 0.449 Oil plus Additive E0.3 6 6 Oil plus Additive of Example 6 0.249

The lubricating oils to which the antiwear agents of the presentinvention may be added include not only mineral lubricating oils butvarious synthetic oils. The mineral lubricating oils may be of anypreferred type including those derived from the ordinary paraffinic,naphthenic, asphaltic or mixed base mineral crude oils by suitablerefining methods. Synthetic hydrocarbon lubricating oils may also beemployed. Other synthetic oils include dibasic acid esters such asdi-Z-ethyl hexyl sebacate, carbonate esters, glycol esters such as C oxoacid diesters of tetraethylene glycol, and complex esters as, forexample, the complex ester formed by the reaction of 1 mole of sebacicacid with 2 moles of tetraethylene glycol and 2 moles of 2-ethylhexanoic acid.

Although the antiwear additives of this invention are primarily intendedfor use in lubricating oils designed for automotive crankcases, they mayalso be employed in other hydrocarbon oil compositions including turbineoils, various industrial oils, hydraulic fluids, transmission fluids andthe like.

The oil compositions may contain other additives such as detergents,sludge dispersers, viscosity index improvers, e.g. polymethacrylates,polybutenes, etc., antioxidants such as phenyl-alpha-naphthylamine,alkyl phenols, bis phenols and the like, pour point depressants, dyes,and other additives for improving the properties of the compositions.

The additives of this invention are particularly applicable for use inlubricating oil compositions containing viscosity index improvers anddetergent-inhibitors. The function of the latter is to prevent orminimize sludge formation as Well as to hold in suspension sludge thatmay be formed in crankcase oils under conditions of low speed, lowtemperature operation, as in stop-and-go driving. In performing theirfunction as sludge inhibitors and sludge dispersers, thedetergent-inhibitors keep the wearing surfaces particularly clean and,for this reason, contribute to a higher degree of wear then would occurif no detergent-inhibitor were present. This problem of wear with highdetergency oils shows up particularly in the valve train of automotiveengines and, especially, in the Valve lifter mechanism, where pressuresas high as 50,000 to 100,000 p.s.i. can exist between the valve lifterand its actuating cam. The additives of the present invention areparticularly effective for reducing wear in this region of the enginewhen it is lubricated with a high detergency motor oil.

Concentrates containing from about 2 to about 8 weight percent ofmolybdenum and from about 10 to about weight percent of surfactant (onan active ingredient basis) in oil are readily prepared by thetechniques of this invention. These concentrates can then be added tolubricant compositions to supply in the finished lubricants from about0.01 to about 2 weight percent of molybdenum. In fluid lubricants theupper range of molybdenum concentration will seldom exceed 1 weightpercent or so, while in grease formulations sufiicient of the additivemay .be used to furnish as much as 2 weight percent of molybdenum.

It is to be understood that the examples presented herein are intendedto be merely illustrative of the invention and not as limiting it in anymanner; nor is the invention to be limited by any theory regarding itsoperability. The scope of the invention is to be determined by theappended claims.

What is claimed is:

1. A process for preparing a stable colloidal complex containingmolybdenum which comprises the steps of preparing an acidic aqueoussolution of a compound of molybdenum selected from the class consistingof molybdic acid and the halogen, ammonium, and alkali metal saltsthereof, said solution having been acidified With a mineral acid to anacidity within the range of from 4 N to 8 N, extracting said acidicsolution with a hydrocarbon ether of from 3 to 8 carbon atoms,dispersing the resultant extract in an oil-soluble dispersant havingsufficient basicity to neutralize the free acidity of said extract, andthen removing ether from the dispersion.

2. A colloidal complex prepared by the process of claim 1.

3. Process as defined by claim 1 wherein said oil-soluble dispersant isemployed as an oil solution.

4. Process as defined by claim 1 wherein said ether removal is effectedby heating the dispersion and blowing the same with a gas selected fromthe group consisting of inert gases and hydrogen sulfide.

5. Process as defined by claim 1 wherein said molybdenum compound ismolybdic acid.

6. Process as defined by claim 1 wherein said molybdenum compound isammonium molybdate.

'7. Process as defined by claim 1 wherein said molybdenum compound is analkali metal molybdate.

'8. Process as defined by claim 1 wherein said dispersant comprises ahigh alkalinity metal salt of a hydrocarbon sulfonic acid having amolecular weight in the range of 300 to 700.

9. Process as defined by claim 1 wherein said dispersant comprises thereaction product of a phosphosulfurized hydrocarbon with a basicsubstance selected from the group consisting of alkaline earth metaloxides and alkaline earth metal hydroxides.

10. Process as defined by claim 1 wherein said dispersant comprises acondenstion product of an alkenylsuccinic anhydride and an aliphaticpolyamine, wherein said alkenyl-succinic anhydride has alkenyl groupstotaling in the range of from about 40 to 250 car-bon atoms.

11. Process as defined by claim 1 wherein said dispersant comprises acondensation product of an alkenyl-succinic anhydride, an aliphaticpolyamine, and a C to C carboxylic acid, said alkenyl succinic anhydridehaving alkenyl groups totaling in the range of from about 40 to 250carbon atoms.

12. An additive concentrate for lubricating compositions consistingessentially of a lubricating oil into which has been incorporated fromabout 10 to about 80 weight percent of an oil-soluble dispersant andfrom about 2 to about 8 weight percent of molybdenum in the form of acolloidal complex prepared by the process of claim 1.

13. A lubricating composition comprising a major proportion of alubricating oil and from about 0.01 to about 2 Weight percent ofmolybdenum in the form of a colloidal complex prepared by the process ofclaim 1.

14. Lubricating composition as defined by claim 13 wherein said etherhas been removed from the dispersion by stripping the dispersion withthe aid of hydrogen sulfide.

References Cited by the Examiner UNITED STATES PATENTS 2,568,876 9/1951White et al. 2525l.5

14 Harle et al. 25249.7 Abbott et al. 25249.7 Matson 25246.4 Anderson etal. 25251.5 Drurnmond et al. 25251.5 Stuart et al. 252515 Price 25233DANIEL E. WYMAN, Primary Examiner.

1. A PROCESS FOR PREPARING A STABLE COLLOIDAL COMPLEX CONTAININGMOLYBDENUM WHICH COMPRISES THE STEPS OF PREPARING AN ACIDIC AQUEOUSSOLUTION OF A COMPOUND OF MOLYBDENUM SLECTED FROM THE CLASS CONSISTINGOF MOLYBDIC ACID AND THE HALOGEN, AMMONIUM, AND ALKALI METAL SALTSTHEREOF, SAID SOLUTION HAVING BEEN ACIDIFIED WITH A MINERAL ACID TO ANACIDITY WITHIN THE RANGE OF FROM 4N TO 8 N, EXTRACTING SAID ACDICSOLUTION WITH A HYDROCARBON ETHER OF FROM 3 TO 8 CARBON ATOMS,DISPERSING THE RESULTANT EXTRACT IN AN OIL-SOLUBLE DISPERSANT HAVINGSUFFICIENT BASICITY TO NEUTRALIZE THE FREE ACIDITY OF SAID EXTRACT, ANDTHEN REMOVING ETHER FROM THE DISPERSION.
 13. A LUBRICATING COMPOSITIONCOMPRISING A MAJOR PROPORTION OF A LUBRICATING OIL AND FROM ABOUT 0.01TO ABOUT 2 WEIGHT PERCENT OF MOLYBDENUM IN THE FORM OF A COLLOIDALCOMPLEX PREPARED BY THE PROCESS OF CLAIM 1.